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authorNick Piggin <npiggin@suse.de>2010-02-01 22:25:57 +1100
committerLinus Torvalds <torvalds@linux-foundation.org>2010-02-02 12:50:47 -0800
commit02b709df817c0db174f249cc59e5f7fd01b64d92 (patch)
treef1e6af927573507e503f3cddfb5bae457a24f72c /mm
parentde5604231ce4bc8db1bc1dcd27d8540cbedf1518 (diff)
downloadlinux-linaro-stable-02b709df817c0db174f249cc59e5f7fd01b64d92.tar.gz
mm: purge fragmented percpu vmap blocks
Improve handling of fragmented per-CPU vmaps. We previously don't free up per-CPU maps until all its addresses have been used and freed. So fragmented blocks could fill up vmalloc space even if they actually had no active vmap regions within them. Add some logic to allow all CPUs to have these blocks purged in the case of failure to allocate a new vm area, and also put some logic to trim such blocks of a current CPU if we hit them in the allocation path (so as to avoid a large build up of them). Christoph reported some vmap allocation failures when using the per CPU vmap APIs in XFS, which cannot be reproduced after this patch and the previous bug fix. Cc: linux-mm@kvack.org Cc: stable@kernel.org Tested-by: Christoph Hellwig <hch@infradead.org> Signed-off-by: Nick Piggin <npiggin@suse.de> -- Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/vmalloc.c92
1 files changed, 81 insertions, 11 deletions
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index cf76ff6ba596..ae007462b7f6 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -509,6 +509,9 @@ static unsigned long lazy_max_pages(void)
static atomic_t vmap_lazy_nr = ATOMIC_INIT(0);
+/* for per-CPU blocks */
+static void purge_fragmented_blocks_allcpus(void);
+
/*
* Purges all lazily-freed vmap areas.
*
@@ -539,6 +542,9 @@ static void __purge_vmap_area_lazy(unsigned long *start, unsigned long *end,
} else
spin_lock(&purge_lock);
+ if (sync)
+ purge_fragmented_blocks_allcpus();
+
rcu_read_lock();
list_for_each_entry_rcu(va, &vmap_area_list, list) {
if (va->flags & VM_LAZY_FREE) {
@@ -678,6 +684,7 @@ struct vmap_block {
DECLARE_BITMAP(dirty_map, VMAP_BBMAP_BITS);
struct list_head free_list;
struct rcu_head rcu_head;
+ struct list_head purge;
};
/* Queue of free and dirty vmap blocks, for allocation and flushing purposes */
@@ -782,12 +789,61 @@ static void free_vmap_block(struct vmap_block *vb)
call_rcu(&vb->rcu_head, rcu_free_vb);
}
+static void purge_fragmented_blocks(int cpu)
+{
+ LIST_HEAD(purge);
+ struct vmap_block *vb;
+ struct vmap_block *n_vb;
+ struct vmap_block_queue *vbq = &per_cpu(vmap_block_queue, cpu);
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(vb, &vbq->free, free_list) {
+
+ if (!(vb->free + vb->dirty == VMAP_BBMAP_BITS && vb->dirty != VMAP_BBMAP_BITS))
+ continue;
+
+ spin_lock(&vb->lock);
+ if (vb->free + vb->dirty == VMAP_BBMAP_BITS && vb->dirty != VMAP_BBMAP_BITS) {
+ vb->free = 0; /* prevent further allocs after releasing lock */
+ vb->dirty = VMAP_BBMAP_BITS; /* prevent purging it again */
+ bitmap_fill(vb->alloc_map, VMAP_BBMAP_BITS);
+ bitmap_fill(vb->dirty_map, VMAP_BBMAP_BITS);
+ spin_lock(&vbq->lock);
+ list_del_rcu(&vb->free_list);
+ spin_unlock(&vbq->lock);
+ spin_unlock(&vb->lock);
+ list_add_tail(&vb->purge, &purge);
+ } else
+ spin_unlock(&vb->lock);
+ }
+ rcu_read_unlock();
+
+ list_for_each_entry_safe(vb, n_vb, &purge, purge) {
+ list_del(&vb->purge);
+ free_vmap_block(vb);
+ }
+}
+
+static void purge_fragmented_blocks_thiscpu(void)
+{
+ purge_fragmented_blocks(smp_processor_id());
+}
+
+static void purge_fragmented_blocks_allcpus(void)
+{
+ int cpu;
+
+ for_each_possible_cpu(cpu)
+ purge_fragmented_blocks(cpu);
+}
+
static void *vb_alloc(unsigned long size, gfp_t gfp_mask)
{
struct vmap_block_queue *vbq;
struct vmap_block *vb;
unsigned long addr = 0;
unsigned int order;
+ int purge = 0;
BUG_ON(size & ~PAGE_MASK);
BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);
@@ -800,24 +856,38 @@ again:
int i;
spin_lock(&vb->lock);
+ if (vb->free < 1UL << order)
+ goto next;
+
i = bitmap_find_free_region(vb->alloc_map,
VMAP_BBMAP_BITS, order);
- if (i >= 0) {
- addr = vb->va->va_start + (i << PAGE_SHIFT);
- BUG_ON(addr_to_vb_idx(addr) !=
- addr_to_vb_idx(vb->va->va_start));
- vb->free -= 1UL << order;
- if (vb->free == 0) {
- spin_lock(&vbq->lock);
- list_del_rcu(&vb->free_list);
- spin_unlock(&vbq->lock);
+ if (i < 0) {
+ if (vb->free + vb->dirty == VMAP_BBMAP_BITS) {
+ /* fragmented and no outstanding allocations */
+ BUG_ON(vb->dirty != VMAP_BBMAP_BITS);
+ purge = 1;
}
- spin_unlock(&vb->lock);
- break;
+ goto next;
}
+ addr = vb->va->va_start + (i << PAGE_SHIFT);
+ BUG_ON(addr_to_vb_idx(addr) !=
+ addr_to_vb_idx(vb->va->va_start));
+ vb->free -= 1UL << order;
+ if (vb->free == 0) {
+ spin_lock(&vbq->lock);
+ list_del_rcu(&vb->free_list);
+ spin_unlock(&vbq->lock);
+ }
+ spin_unlock(&vb->lock);
+ break;
+next:
spin_unlock(&vb->lock);
}
+
+ if (purge)
+ purge_fragmented_blocks_thiscpu();
+
put_cpu_var(vmap_block_queue);
rcu_read_unlock();